In recent years, a multicarrier system, particularly an orthogonal frequency division multiple access system (Orthogonal Frequency Division Multiple Access: OFDMA), is attracting attention as a multiple access system of a wireless communication system.
If the same subcarrier is used between cells when OFDMA is applied to a cellular environment, the cells interfere one other, and the throughput decreases. Therefore, in the cell on the side that causes the interference, measures are proposed, such as reducing the transmission power of the subcarrier or not using the subcarrier.
One of the techniques applying such measures is disclosed in Patent Document 1.
In the technique disclosed in Patent Document 1, a wireless network controller (Central Entity: CE) connected to base stations (Base Station: BS) allocates wireless resources (time/frequency groups) of the base stations.
Terminals (Terminal: T) receive pilot signals from the base stations, respectively, measure the reception strength of the pilot signals, and notify the base stations of the measured reception strength. The base stations transfer information of the reception strength notified from the terminals to the wireless network controller.
Based on the information of the reception strength of the terminals, the wireless network controller allocates the time/frequency groups to the base stations and notifies the base stations of the allocation information.
The base stations transmit data to the terminals located in the cells of the base stations in accordance with instructions of the allocation information of the time/frequency groups notified from the wireless network controller.
In the technique disclosed in Patent Document 1, upon allocation of the time/frequency groups, a transmitted useful signal and interference as a result are adjusted at the same time, or a transmitted useful signal and the same signal transmitted from two or more neighborhood base stations are adjusted at the same time.
If the same signal is not transmitted from the neighborhood base stations, the former “a transmitted useful signal and interference as a result are adjusted at the same time” is performed.
Patent Document 1 specifically illustrates a method, in which each base station allocates frequency groups to the terminals located in the cell of the base station, and the transmission power of the frequency groups allocated to the terminals located in a service overlapping area between the base stations, in other words, the terminals located near a cell boundary, is reduced for the terminals located in the cells of adjacent base stations.
The throughput of the terminals located near the cell boundary is expected to rise in the method. However, there is a problem that the throughput of the terminals, which are located in the cells of the adjacent base stations and in which the transmission power is reduced, is reduced and that an increase in the throughput of the entire system is not guaranteed.
There is also a problem that an increase in the fairness of the entire system is not guaranteed when proportional fairness for scaling the fairness in the allocation of wireless resources to the terminals is applied.
Furthermore, there is a problem that which transmission power is prioritized when the same frequency groups as the terminals located in the cells of the adjacent base stations are allocated to the terminals located near cell boundary is not clear in Patent Document 1 and that a correspondence method is not generally known.    Patent Document 1: JP2006-033826A